"We don't really know how to handle tens of thousands of potentially lethal experimental robotic pilots buzzing around dense cities. Before consumers can get an order of Xanax from an Amazon delivery drone, we might want to make sure it gets to the destination without harming anyone in the process."

Finally, many are retweeting this image of what a "we attempted a drone delivery" note might look like. It's got another Terminator-type warning: "Drone reached sentience and defected to join the machines in the upcoming revolution against mankind."

For the record, Amazon promises that "safety will be our top priority, and our vehicles will be built with multiple redundancies and designed to commercial aviation standards.

On All Things Considered, NPR's Brian Naylor reports that one challenge Amazon would have to overcome is the Federal Aviation Administration's view that drone operators would need to have "a line of sight to the aircraft." In other words, they would have to be able to see where it's going. That's not what Amazon envisions — automated flights from centralized locations to customers within a 10-mile-or-so radius.

Should the rules be worked out to Amazon's satisfaction, though, Pepperdine Law School professor Greg McNeal sees one way customers could guarantee their deliveries get to the right place: By getting a "sort of landing pad that can transmit GPS coordinates" to the drone.